This invention relates to a diamino compound, a poly(amic acid) resin, a poly(amic acid) ester resin, a polyimide resin, processes for producing them, photosensitive resin compositions containing said resins, and polyimidazopyrrolone resins or polyimidazopyrroloneimide resins obtained from said resins or from photosensitive resin compositions containing said resins.
In the current semiconductor industry, the inorganic materials having hitherto been used as an interlaminar insulating material are being replaced by organic materials excellent in heat resistance and particularly by polyimide resin and the like because of their excellent properties.
Since the formation of a circuit pattern on a semiconductor integrated circuit or a printed circuit involves complicated and divergent procedures such as resist film formation on the substrate surface, exposure of necessary areas to light, removal of unnecessary areas by etching or the like, cleaning of the substrate surface, etc., it is waited for to develop a heat-resistant photosensitive material which makes it possible to leave the resist material of necessary parts as it is in order to use it as an insulating material even after patterns have been formed by exposure and development.
As such materials, heat-resistant photosensitive materials using a photosensitive polyimide, a cyclized polybutadiene or the like as a mainly used polymer have been proposed. Among them, photosensitive polyimide is-noticed with a particular interest because it is excellent in heat resistance and the removal of impurities therefrom is easy to practice. As one example of such photosensitive polyimide, Japanese Patent Examined Publication No. 55-30207 proposed a photosensitive polyimide precursor prepared by introducing a photosensitive group into a polyimide precursor through an ester bonding. However, this material is disadvantageous in that, since an acid chloride is used in the synthesis of the photosensitive polyimide precursor, the finally obtained photosensitive resin composition is readily contaminated by chloride. Further, this resin is difficult to make into a material of high molecular weight, so that it is inferior in film strength.
As another example, Japanese Patent Unexamined Publication No. 57-168942 proposed a photosensitive composition comprising a mixture of a poly(amic acid) and an amine having photo-crosslinkable functional group as its main ingredient. However, this photosensitive composition is disadvantageous in that the bonding force between poly(amic acid) and the photosensitive functional group is relatively weak and therefore this composition is low in the development latitude.
In Japanese Patent Unexamined Publication No. 54-95697, there is proposed a photosensitive composition comprising a mixture of poly(amic acid) and a polymerizable unsaturated compound having acryl functional group or the like as its main ingredient. However, this composition is narrow in its development latitude due to a small difference between the solubility of non-exposed areas to a developer and that of exposed areas to the developer. The term "development latitude" means a time between the minimum time necessary for removing non-exposed areas by development and the maximum time not corroding exposed areas by development. The larger the development latitude, the better the workability.